Nonwoven abrasive articles generally have a nonwoven web (e.g., a lofty open fibrous nonwoven web), abrasive particles, and a binder material (commonly termed a “binder”) that bonds the fibers within the nonwoven web to each other and secures the abrasive particles to the nonwoven web. Examples of nonwoven abrasive articles include nonwoven abrasive hand pads and surface conditioning abrasive discs and belts such as those marketed by 3M Company of Saint Paul, Minn. under the trade designation SCOTCH-BRITE.
Nonwoven abrasive wheels are another type of nonwoven abrasive article. Examples of nonwoven abrasive wheels include convolute abrasive wheels (spirally wound nonwoven abrasive web around a core) and unitized abrasive wheels (one or more individual discs of nonwoven abrasive web formed into a stack). Nonwoven abrasive wheels are also available from 3M Company of Saint Paul, Minn. under the trade designation SCOTCH-BRITE.
In one manufacturing method, a nonwoven fiber web is coated with a binder precursor material. Next, abrasive particles are adhered to the binder precursor material, which is then cured to secure the abrasive particles to the fiber web.
Historically, lofty, open, non-woven abrasive articles have been made using a variety of coating techniques. For example, in the U.S. Pat. No. 2,958,593 (Hoover et al.), nonwoven abrasive articles were made by the spray application of a relatively dilute slurry comprising a solution of a binder, solvent, and abrasive particles. In another method, the abrasive particles may be applied by a drop coating method as described in PCT Internat. Publ. No. WO 2014/137972 Al (Kaur et al.).
U.S. Pat. No. 6,017,831 (Beardsley et al.) describes yet another a coating technique in which a uniformly dispersed cloud of fine abrasive particles is deposited (preferably by settling due to gravity) onto binder precursor-coated fibers. Use of electrostatic coating to orient abrasive particles and bond them to a lofty nonwoven material is described in U.S. Pat. No. 7,393,371 (O'Gary et al.).